Photo of the day

A pile of drowned wildebeest wash up on the bank of the Mara. (Amanda Subalusky)

Sometimes, everything goes wrong. The river might be especially deep or strong at that point. The opposite bank could be slippery or steep. The herd might be too big. Aggressive tourists can push them to more dangerous crossing points. “If there’s anything that keeps them from getting out on the other side, they’ll start to pile up. And even as they’re drowning on one side of the river, there are still wildebeest following them in.”

The result is an annual mass drowning. “We’ve seen up to 300 carcasses wedged into the river bank in some places,” says Subalusky. “It’s quite a sensory experience. The smell is potent for a quarter mile, and lasts for weeks. There’s a ranger station nearby and they really hate it when the drownings happen.”

She and her colleagues, including husband Chris Dutton and supervisor David Post, spent five years studying the migrating wildebeest, counting their corpses as they floated downstream. Through their sometimes grisly work, they’ve shown that these drowning herds account for a shocking large proportion of the river’s nutrients. Disney symbolized the circle of life with a lion cub being held aloft by a monkey. It might have done better with a mound of rotting, sodden wildebeest carcasses.

“Even when people noticed these drownings, it’s easy to underestimate the size and frequency of them,” says Subalusky. Her team estimated that around five mass drownings (defined as events involving at least 100 dead wildebeest) happen every year. Together, these events create around 6,000 carcasses and 1,100 tons of dead meat—roughly like dumping ten blue whales into the river every year.